The use of lasers for the treatment and/or diagnosis of eye tissue is known. Such devices, for example, have a basic device with a laser light source for generating laser pulses, for example femtosecond laser pulses, and an application head with a projection objective which, for treatment, is coupled with the eye of the patient. The application head can be movably connected to the basic device, for example, by means of an articulated arm, wherein the articulated arm can simultaneously be used for the optical beam guidance from the laser light source to the application head. For example, such an arrangement is disclosed in EP 1 731 120. There are also devices with the application head integrated in the basic device or in which other device arrangements are provided.
The application head is mechanically and optically coupled to the eye of the patient, for example, to the cornea or the sclera of the eye of the patient, by means of a patient interface, wherein the patient interface can comprise a transparent contact body, with which the laser pulses emerging from the projection objective are guided and which, by means of mechanical contact with the cornea, secures said cornea with regard to the patient interface and the projection objective. Alternatively to coupling by means of a contact body, a liquid coupling can be provided, wherein a coupling liquid, for example, physiological salt solution, is located between cornea and projection objective. Corresponding patient interfaces, for example, are known from WO2012031277. The patient interface can be coupled to the eye of the patient by means of a vacuum and a suction ring placed on the cornea. Most suction rings have two sealing lips. The lips can be applied to the sclera, the sclera and the cornea, or only the cornea. Furthermore, there are variations which have only one ring and generate a vacuum across the entire eye, or variations consisting of a plurality of suction chambers/suction cups. The suction ring is the most common attachment method, however, there are also other known solutions. With the known systems, the patient interface is coupled to the application head, for example, by means of a screw connection, bayonet connectors, or vacuum couplings
U.S. 2008/287927 describes a protective device for ophthalmic laser treatment using a protective foil for protecting the eye from direct contact with a reference body arranged between the application head and the eye. The protective device comprises a suction ring for attachment to the eye and is designed to receive the protective foil, for example, by means of an annular carrier frame. The suction ring is provided with coupling means for attachment to the application head. According to U.S. 2008/287927, the coupling means are designed as screw connection, bayonet connector, or snapping mechanism.
U.S. 2012/0283708 describes an ophthalmological patient interface which can be coupled to an application head of a laser system and has a contact lens to be disposed on the eye. U.S. 2012/0283708 describes a flexible connection element attached to the contact lens which allows for a rotational and/or transversal movement of the contact lens relative to the application head during docking. Without further description, the document cites a “flex-and-lock” mechanism for inhibiting further movement of the contact lens relative to the application head.
For patient interfaces used in ophthalmological laser applications, there are a number of challenges and marginal conditions which make the transfer of numerous constructions known from other areas of application appear to be impossible or impractical from a practical point of view. Significant limitations result from the existing proximity of the devices to the eye of the patient and particularly the direct physical contact of the patient interface with the eye of the patient. In addition to high safety requirements, it follows that the patient interface is at least designed to be easily manageable and securely attachable.
Even though the space conditions in the vicinity of the operating site on the eye of the patient are narrow and crowded, the eye of the patient should be accessible and visible to the user during treatment. Patient interface and the other components should thus interfere very little with accessibility and visibility.
Due to the significant medical risks in case of a misdirection of the laser beam which can result in unwanted impairment and even destruction of eye tissue, components which are arranged in the region of the beam path from the light projector to the eye of the patient must be positioned and aligned correctly and safely coupled or connected to one another.